Unfortunately Bay loves his army guys running around and sticking their oar in. The Autobots would have put up a valiant fight and it would have been a close call, but with Prime down, they wouldn't have been able to take Megatron out. Let's not forget that Megatron is one hard mo'fo' and the rest of the Autobots are pretty much scared of him. Bee took a few out in style and Ironhide, Ratchet and Sideswipe would be able to hold their own but I don't think they'd be able to take on all the D-Cons... especially with Starscream circling the scene. Jetfire is tough, but Skorpinox highlighted his weakness.

I think the D-Cons would have won. Not to mention the small matter of the Fallen and Devastator putting a spanner in the works.

I agree that the Autobots would win eventually. But the Autobots would only win if Prime managed to take down Megatron once and for all. The guy just doesn't know how to stay down. He takes on so much damage but carries on regardless - the forest fight scene epitomised that. Prime must have punched, kicked, kneed, elbowed and stabbed him about 20 times but he just keeps getting up. He is an absolute legend!

Without the military the Autobots still would have found a way to win the day because that's what movie heroes do. Heroes just find that way to beat the odds and that's what puts them above your average Joe like the Bride taking on the Crazy 88's by herself or Batman having to deal with the Joker goons and Gotham PD before taking on the Joker.

If the human military wasn't the most powerful thing in the Transformers universe then the Autobots would have had the chance to shine as the real heroes of the film instead of playing second fiddle to the humans. Even if Prime went down some Autobot would rise to the occasion just as Luke Skywalker had to rise to the occasion after Ben gets cut down by Vader.

As cool as it is to see all that military gear in action I sort of wish the humans had some other film to show that off in. With the humans taking out Decepticons with air strikes and rail guns it feels like if you had gotten to the end of Aliens 2 and instead of Ripley taking on the Alien Queen by herself a squad of space marines showed up out of nowhere and killed the Queen with a few shots robbing Ripley of her chance to be one of the great movie heroes.

The Autobot-Decepticon war is supposed to have raged for god knows how long on Cybertron, so obviously the Autobots were not able to ever fully beat the Decepticons on their own. I think this is why the Autobot-human alliance in the movies so far is supposed to be so important; the additional aid of the human military provides the Autobots with more support in their battle against the D-cons that they did not have before, hence why the D-cons have been for the most part obliterated on Earth in the movies. It's the combined force of the Autobots and the human military that allowed such a victory over their enemies.